The present invention relates to novel hybrid coated cosmetics powders and methods of making and using same. More particularly, the invention relates to novel compositions and methods for coating insoluble cosmetics powders, for example inorganic and organic, pigments and fillers, to the coated powders produced, to cosmetic and other formulations incorporating such coated powders and to methods of making and using said coated powders and formulations. Preferred embodiments of the invention include novel coated cosmetic powders having a unique combination of excellent hydrophobic and lipophilic properties which is particularly advantageous in many cosmetic applications.
Most cosmetics formulations include in their compositions cosmetic powders, finely divided particles of solid, insoluble materials, for example pigments and fillers, that can serve a variety of functions, such as providing desired visual properties such as opacity and color, desired tactile properties such as viscosity and feel, special effects such as pearlescence and iridescence and various other desirable properties, for example oil absorbency. Cosmetic powders include inorganic materials such as metal oxides, silicates and carbonates as well as organic pigments or lakes such as ultramarine and crimson lake and polymeric particulates such as nylon and cellulose. Additional examples of pigments that can be employed in the present invention are set forth hereinbelow. Some examples of cosmetic formulations employing powders include liquid or powder makeups and foundations, moisturizing and antiaging creams and lotions, nail polish, lipstick, mascara and eye shadow, to name but a few.
Primarily because of their surface characteristics, it may be difficult to satisfactorily incorporate raw, untreated powders into liquid or powdered cosmetic bases or excipients in a manner providing uniform stable dispersions. Desirably, the powders should be uniformly distributed throughout the base or excipient medium and the dispersion should remain stable over time with no significant settling or agglomeration occurring before the product is eventually used by the end consumer, which can be as much as two or more years after manufacture. It is also desirable that the powders should not impart unaesthetic characteristics to the end-product cosmetic formulation, such as a gritty or sandy feel, which may result from agglomeration of powder particles or the presence of oversized particles in the pigment powder, discoloration attributable to non-uniform distribution of the powder, and other negative characteristics such as settling.
Many pigment materials for example metal oxides and carbonates, have a somewhat hydrophilic surface, or bear hydrophilic moieties or ions on their external surfaces which render the powder particles prone to agglomerate in aqueous media which are commonly employed in cosmetics.
Accordingly, over the years, many compositions and methods have been employed and proposed for treating or coating insoluble cosmetic powders, in order to overcome these and other problems. Such prior proposals have met with considerable success and it is now standard practice in the cosmetics industry to coat powders for cosmetic use. In particular, it is well known to “hydrophobize” cosmetic powders, which is to say to treat the powders to render them more hydrophobic, thus providing more stable dispersions (or suspensions) in aqueous media.
Powders can be hydrophobized by treatment with a suitable coating agent in a liquid medium, for example by mixing or spraying the coating agent with or on to the powder and heating the mixture, optionally under vacuum to remove volatile solvents, if employed. Preferred coating agents are chemically reactive with the substrate powder to provide a durable covalent bond thereto and have hydrophobic chemical backbones or substituents that can provide a hydrophobic outer layer, skin or shell around each individual powder particle. The coating agent may react, for example, with hydroxyl groups, oxide ions, available oxygen atoms or other suitable reactive groups normally present on the surface of the cosmetic powder being coated.
Mitchell Schlossman U.S. Pat. No. 4,877,604 (“Schlossman '604” hereinafter), the disclosure of which is herein incorporated by reference thereto, discloses and claims the use of organotitanates, to coat pigments and other cosmetic powders, one preferred coating agent being isopropyl titanium triisostearate. Schlossman '604 discloses that the claimed coating materials and methods can provide uniform and stable dispersions of pigments and other cosmetic materials, such as talc, sericites and mica. Such dispersion uniformity can avoid the need to colloid mill the final emulsion to achieve smoothness and homogeneity in various cosmetic products, for example, in oil-in-water liquid makeups, avoiding settling or segregating out of pigments or other cosmetic material thereby increasing the shelf-life of the product. In addition, the use of Schlossman '604's titanate-treated pigments in liquid pigment and/or color extenders can improve the viscosity range providing more uniform extenders and enabling extenders to be utilized without adversely affecting the viscosity of the final product.
Other advantages to using treated or coated materials in accordance with Schlossman '604 include increased water resistance due to hydrophobic characteristics, reduced need for powder blends, increased smoothness on application of anhydrous and powder blends, better skin adhesion, better appearance of frosted products, less streaking in pressed and anhydrous makeup products and noticeable smoothness and ease of manufacture of compact cream makeup.
Thus, the Schlossman '604 organometallate coating materials provide an array of attractive features. Pursuant to the insights of the invention, it would be desirable to provide coatings for cosmetic powders which retain these benefits and which can extend potential uses of the resultant coated powders to environments where isopropyl titanium triisostearate treated pigment may not always be satisfactory, for example in silicone fluids and in low pH media. The latter are often required for skin care products containing alpha-hydroxy acids.
It is also known to employ functionalized silanes, including for example, triethoxy octylsilane to provide a silicone coating on cosmetic powders to render them hydrophobic. With regard to terminology, it is notable that even extensively substituted derivatives of silane, such as triethoxy decyl silane are sometimes generally referenced in the art by the catch-all phrase “silanes”. While silane-coated powders may display good hydrophobicity they may not be adequately lipophilic for some purposes yielding unacceptably viscous dispersions in cosmetic oils such as mineral oil. A further problem is that silicone coated pigments may display color shift over time. Hollenberg et al. U.S. Pat. No. 5,143,722 is but one example of a disclosure of silane coated cosmetic pigments providing silicone coated pigment powders.
The foregoing description of background art may include insights, discoveries, understandings or disclosures, or associations together of disclosures, that were not known to the relevant art prior to the present invention but which were provided by the invention. Some such contributions of the invention may have been specifically pointed out herein, whereas other such contributions of the invention will be apparent from their context. Merely because a document may have been cited here, no admission is made that the field of the document, which may be quite different from that of the invention, is analogous to the field or fields of the invention.